The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
In a wireless network (such as, for example, a 3rd Generation Partnership Project (3GPP) evolved wireless network, a wireless terminal may request to attach to the wireless network via an attach procedure. The wireless terminal may include user equipment (UE) in the 3GPP wireless network. For example, the wireless terminal may include a mobile phone, and the wireless network may be the cellular network of a mobile phone operator. Conversely, the wireless terminal may include a laptop computer or other mobile computing device, and the wireless network may be a local area network (LAN) or Internet service provider (ISP). The wireless network allocates an IP address to the wireless terminal during the attach procedure.
Referring now to FIGS. 1-3, exemplary wireless networks that may implement the attach procedure are shown. As shown in FIG. 1, a home network 102 receives packets from and sends packets to a distributed communications system 104 such as the Internet. A wireless terminal 106 wirelessly connects to the home network 102. As shown in FIG. 2, the home network 102 is connected to one or more visited networks 110. For example only, FIG. 2 depicts three visited networks 110-1, 110-2 and 110-3. In various implementations, the visited networks 110 may be the networks of other service providers, including service providers in other countries. A mobile wireless terminal 120 includes mobility features that allow the mobile wireless terminal 120 to communicate with the visited networks 110.
Referring now to FIG. 3, a functional block diagram depicts a wireless communications system that provides proxy mobility to the wireless terminal 106. A home network 150 communicates with visited networks 160-1, 160-2, and 160-3. The visited networks 160 provide transparent mobility to wireless terminals, such as the wireless terminal 106, that have not been updated to include mobility functionality.
As described above with respect to FIGS. 1-3, the wireless terminal may attempt to establish a link with one of the home network 102, a visited network 110, and/or a visited network with mobility 160 via an attach procedure. Attachment to visited networks and visited networks with mobility are described in more detail in U.S. patent application Ser. No. 12/009,725, filed Jan. 22, 2008, which is incorporated herein by reference.
Referring now to FIG. 4, a timeline of steps performed when the wireless terminal 106 connects to the network 102 (i.e. an attach procedure) is shown. The attach procedure 200 includes interaction between the wireless terminal 106 and one or more nodes of the network 102, including, but not limited to, a mobility management entity (MME) 202, a serving SAE (system architecture evolution) gateway 204, a packet data network (PDN) SAE gateway 206, a policy and charging rules function (PCRF) 208, and a home subscriber server (HSS) 210. For example only, the wireless terminal 106 may include a UE device and an enhanced or evolved node B (eNB) wireless base station.
The wireless terminal 106 performs authentication and identification with the network 102. This may include communicating with an Access, Authentication, and Accounting (AAA) server. During authentication and identification, the wireless terminal 106 transmits an attach request to the MME 202. The MME 202 requests an identity of the wireless terminal 106 and authenticates the identity with the HSS 210. Upon authentication, the PDN SAE gateway 206 allocates an Internet protocol (IP) address to the wireless terminal 106 and accepts the attach request. The wireless terminal 106 completes the attach. The attach procedure 200 may include other network-side steps unrelated to IP address allocation, such as clearing previous bearer context requests and updating locations.